Lockout mechanism for surgical apparatus

ABSTRACT

A self contained gas powered endoscopic surgical apparatus is provided for placing lateral lines of surgical fasteners into body tissue. The apparatus includes an anvil member and a surgical fastener cartridge member mounted to the distal end of an elongated endoscopic portion. A tubular collar of the endoscopic portion moves distally to engage the anvil member and bias the anvil member and the cartridge member into cooperative alignment, thereby clamping body tissue to be fastened between the anvil member and the cartridge member. A self contained pneumatic system is disposed in the surgical apparatus and is actuable to eject and/or form the surgical fasteners in the clamped body tissue. The apparatus further comprises a locking member for preventing approximation of the anvil member and the cartridge. In one embodiment a clamping interlock is shown which prevents approximation of the jaws when the jaws are either misaligned or improperly inserted into the instrument. In a second embodiment a clamping interlock is shown which directly engages the tubular collar preventing approximation of the jaws when a cartridge member is not fully inserted. In a third embodiment a clamping interlock is shown which directly engages the tubular collar when an unfired cartridge is not present or properly inserted into the instrument.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/915,425, filed Jul. 17, 1992, now abandoned, which is acontinuation-in-part of application Ser. 1991, 07/781,012, filed Oct.18, 1991 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to surgical stapling apparatus, and moreparticularly to surgical apparatus which are powered by self containedrelatively low pressure gas systems to perform sequential operationssuch as tissue clamping, staple forming and/or tissue cutting.

2. Description of Related Art

Surgical stapling apparatus is known wherein tissue is first grasped orclamped between opposing jaw structure and then fastened by means offasteners. In some instruments a knife is provided to cut tissue whichhas been joined. The fasteners are typically in the form of surgicalstaples however, two part polymeric type fasteners are also known.

Instruments for this purpose can comprise two elongated fingers whichare respectively used to capture or clamp tissue. Typically, one of thefingers carries a disposable cartridge housing a plurality of staplesarranged in at least two lateral rows while the other finger comprisesan anvil for curling the staple legs into hook form upon their beingdriven against the anvil. The stapling operation is effected by a pusherwhich travels longitudinally along the cartridge carrying finger, withthe pusher acting upon the staples to place rows of staples in bodytissue. A knife may optionally be positioned to operate sequentiallyimmediately behind the pusher and laterally positioned between thestaple rows longitudinally cut and/or open the stapled tissue betweenthe rows of staples. Such instruments are disclosed in Bobrov et al.(U.S. Pat. No. 3,079,606) and Green (U.S. Pat. No. 3,490,675). Theinstruments disclosed therein comprise apparatus for simultaneouslymaking a longitudinal incision and applying a row of staples on bothsides of an incision.

A later development disclosed in Green (U.S. Pat. No. 3,499,591) appliesa double row of staples on each side of the incision. This isaccomplished by a cartridge assembly wherein a cam member moves within aguide path between two sets of staggered staple carrying grooves. Stapledrive members located within the grooves each have two staple pusherplates, and sloping surfaces disposed within the guide path so as to becontacted by the longitudinally moving cam and be driven along thegroove to effect ejection of two staples.

The cartridge assemblies typically come in a plurality of sizes, eachvarying in both length and number of staples contained therein.Depending on the procedure to be performed, the surgeon must select theappropriate cartridge assembly. No provision is currently available toadjust the firing means of the instrument itself so that a wide varietyof staple driving sequences may be accomplished using a single staplecartridge assembly.

The instruments described above were all designed to be used in surgicalprocedures wherein surgeons have direct manual access to the operationsite. However, in endoscopic or laparoscopic procedures surgery isperformed through a small incision or through narrow cannulae insertedthrough small entrance wounds in the skin. In order to address thespecific needs of endoscopic and/or laparoscopic surgical procedures, anendoscopic surgical stapling apparatus such as that shown in Green etal. (U.S. Pat. No. 5,040,715) has been developed. This apparatus is wellsuited for such procedures and incorporates a distal end having an anviland staple cartridge assembly and a manually operated handle assemblyinterconnected by an endoscopic portion which permits the instrument tobe inserted into a cannula and be remotely operated by the surgeon.

The instruments discussed above all require some degree of manuallyapplied force in order to clamp, fasten and/or cut tissue. This manualapplication can prove awkward or difficult depending upon theorientation of the instrument relative to the surgeon, the type oftissue being operated on or the strength of the surgeon. Furthermore,because of the difficulty and expense of cleaning and sterilizingsurgical instruments between uses, there is increasing interest in anddemand for instruments which are disposable after use in a singlesurgical procedure rather than permanent and reusable. And because ofthe greater convenience and ease of using self-powered instruments aswell as the more uniform results typically produced by self-poweredinstruments (as compared especially to manually powered instruments),there is increasing interest in and demand for instruments which areself-powered. Accordingly, there is a need for a self-powered endoscopicsurgical apparatus to alleviate these difficulties.

Self contained gas powered surgical staplers are known, as shown, forexample, in U.S. Pat. Nos. 3,618,842; 3,643,851; 3,662,939; 3,717,294;3,815,476; and 3,837,555. Typically, these staplers include areplaceable cylinder which supplies gas (e.g., carbon dioxide ornitrogen) at relatively high pressure (e.g., 800 p.s.i.g.) for poweringthe instrument. The high pressure gas used in these staplers requiresthat the staplers be of relatively heavy construction in order to safelyaccommodate the high pressure involved. Because of their construction,these instruments are relatively expensive to manufacture and thereforegenerally intended to be relatively permanent and reusable.

Use of a relatively low pressure gas is advantageous to enable a staplerto be made of lighter construction and less expensive materials. This isdesirable to lower the cost and make the stapler economicallydisposable. The stapler must, however, be capable of generating thesubstantial forces required to form the staples. Typically, the staplesare metal wire which is partially formed prior to use and which must befurther formed (e.g., crimped against an anvil) by the stapler. Togenerate the relatively large forces required to form the staples withlow pressure gas would ordinarily require a relatively large pneumaticactuator. This is undesirable because a large actuator makes the staplerbulky and difficult to work with. In addition, a large actuatorunnecessarily consumes a large amount of gas during the portion ofactuator motion when relatively large forces are not required, i.e.,during the first part of the actuator stroke when the staple is merelybeing advanced to the staple forming position. The gas which is thuseffectively wasted substantially reduces the number of staplingoperations which can be performed by the stapler before its gas supplyis exhausted. This substantially shortens the useful life of the staplerif the gas supply is not replaceable, and even if the gas supply isreplaceable, it undesirably increases the frequency with which the gassupply must be replaced.

Although it is desirable to perform most of the functions of thestapling apparatus automatically using the self-powering elements in theapparatus, it may also be desirable for the initial function to be atleast partly manual. For example, if the initial function is tissueclamping, it is preferably initiated manually so that it can beperformed slowly and precisely and the results inspected and correctedif necessary before the automatic self-powered portion of the operatingsequence begins. See, for example, U.S. Pat. Nos. 4,349,028 and4,331,277 to Green.

Accordingly, there is a present need for a self contained gas poweredsurgical instrument for driving surgical fasteners into body tissuewhich instrument can be made of lighter materials and can be madedisposable after use.

Because endoscopic procedures are more common than laparoscopicprocedures, the present invention shall be discussed in terms ofendoscopic procedures and apparatus. However, use herein of terms suchas "endoscopic", "endoscopically" and "endoscopic portion", amongothers, should not be construed to limit the present invention to astapling and cutting apparatus for use only in conjunction with anendoscopic tube. To the contrary, it is believed the present inventionmay find use in any procedure where access is limited to a smallincision, including but not limited to laparoscopic procedures. Also, asused herein the terms "fasteners" and "staples" shall be treatedequivalently. Unless otherwise stated, the term "cartridge assembly"shall include at least the cartridge itself and staples or fasteners andstaple drive members disposed therein.

3. Objects of the Invention

Accordingly, it is one object of the present invention to provide a selfcontained gas powered surgical apparatus for driving fasteners into bodytissue.

It is another object of the present invention to provide a selfcontained endoscopic surgical apparatus which is powered by a lowpressure pneumatic system contained within the apparatus.

It is yet a further object of the present invention to provide a selfcontained gas powered surgical apparatus insertable through a smallincision or narrow tube for driving surgical fasteners into body tissueand cutting the body tissue between rows of staples.

Another object of the present invention is to provide a self containedgas powered surgical apparatus which is disposable after use.

A further object of the present invention is to provide a self containedgas powered surgical apparatus which may be selectively set to drivesurgical fasteners in a variety of sequences.

Another object of the present invention is to provide a self containedgas powered surgical apparatus which is activatable to move through anentire sequence of operation by a single press of the actuator.

A further object of the present invention is to provide a self containedgas powered surgical apparatus having a gas metering element to preventfiring of the staples from the cartridge unless a sufficient quantity ofgas is available to move the driving member through a full sequence ofoperation.

Another object of the present invention is to provide a self containedgas powered surgical apparatus having a clamping lockout mechanism whichwill prevent clamping of tissue unless the cartridge has been properlyinserted in the instrument.

A further object of the present invention is to provide a surgicalapparatus having a clamping lockout mechanism which directly engages acamming collar to prevent approximation of an anvil and cartridge.

Another object of the present invention is to provide a surgicalapparatus having a clamping lockout mechanism which will preventclamping of tissue unless an unfired cartridge is fully seated in theinstrument.

A further object of the present invention is to provide a self containedgas powered surgical apparatus having sealing structure for inhibitingthe escape of gas through the apparatus.

Another object of the present invention is to provide a self containedgas powered surgical apparatus having counter structure for displayingthe number of times the instrument has been fired.

A further object of the present invention is to provide a self containedgas powered surgical apparatus with lockout structure to disable theapparatus after a predetermined number of firings.

SUMMARY OF THE INVENTION

These and other objects of the invention are accomplished in accordancewith the principles of the invention by providing a self containedendoscopic surgical instrument which is at least partially operable bymeans of a relatively low pressure pneumatic assembly. Advantageously,the surgical instrument in accordance with an embodiment of the presentinvention is a surgical stapling apparatus adapted for placing one ormore longitudinal rows of staples. This apparatus may further include aknife for making an incision in body tissue between rows of staples. Thelatter configuration may find particular use of adjoining two holloworgans or in removing an organ, such as the appendix, the gallbladder,etc.

The self contained gas powered surgical instrument of the presentinvention in an endoscopic stapler configuration comprises a frame; anendoscopic portion defining a longitudinal axis and extending distallyfrom the frame, the endoscopic portion including an elongated housinghaving a distal member for mounting a cartridge assembly. The cartridgeassembly includes a plurality of surgical staples slidably mountedtherein and has a tissue engaging surface. An anvil member is alsoprovided and has a staple forming surface and a proximal end mounted tothe elongated housing such that the anvil member is movable between anopen position and a closed position such that the staple forming surfaceis in close cooperative alignment with the tissue engaging surface ofthe cartridge assembly.

The instrument further includes structure for moving the anvil memberbetween the open and the closed positions and structure for ejecting thesurgical staples from the cartridge assembly to cause the staples toengage and form on the staple forming surface of the anvil member.

A self contained pneumatic system is disposed in the frame and includesa supply of relatively low pressure gas connected to a pneumaticactuator mechanism. The pneumatic actuator mechanism actuates thestructure for ejecting the surgical staples from the cartridge assembly.

The surgical instrument may be constructed either as a reusable unit oras a single use, disposable unit or, alternatively may be formed with areusable handle portion and replaceable staple carrying cartridges.

The present invention advantageously permits surgeons to performinternal surgical procedures including stapling and/or cutting simply bymanually clamping the tissue to be manipulated and pneumaticallyactuating the jaw members. This results in greater convenience and easeof use of the instrument as well as more uniform actuation of theinstrument mechanisms.

The stapler embodiment of this invention is preferably controlled by amanually operable trigger or other similar control. Momentary operationof the trigger initiates an operating cycle of the stapler whichnormally is automatically completed without continued actuation of thetrigger. A safety interlock may also be employed in cooperation with thetrigger mechanism to prevent accidental actuation. Preferably thestapler performs only one operating cycle in response to each operationof the control regardless of the length of time the control is operatedbeyond the time required to initiate an operating cycle. The stapleralso cannot begin a new operating cycle until the preceding cycle iscomplete. Also, a safety mechanism may be incorporated to preventclosure of the jaws if they are misaligned or improperly inserted. In aparticularly preferred embodiment of the invention, the operating cyclewill not begin unless sufficient gas remains in the reservoir to propelthe instrument through a complete cycle. Alternatively, structure may beprovided to give a visual or tactile indication of the number of timesthe instrument has been fired and/or lock out the operating cycle aftera given number of firings. Sealing means may be provided to moreefficiently seal the apparatus and prevent excess gas from passingthrough the interior thereof.

In another particularly advantageous embodiment of the invention thesurgical element includes adjustment structure which permits theinstrument to be selectively preset to fire in a predetermined sequenceto drive a given number of staples and/or rows of staples.

In other preferred embodiments of the invention, clamping lockout meansare provided to prevent the approximation of an anvil and cartridge orother surgical jaw means when a cartridge is not properly and fullyinserted into the instrument. Preferred embodiments of the clampinglockout structure also provide means for preventing the reapproximationof the anvil and cartridge after the instrument has been fired.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawing and the followingdetailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described hereinbelow withreference to the drawings. In the drawings and the description whichfollows, "proximal" means the end closest to the operator and "distal"means the end furthest from the operator.

FIG. 1 is a perspective view of a self contained gas powered endoscopicsurgical instrument in accordance with one embodiment of the presentinvention;

FIG. 2 is an exploded perspective view of the frame and pneumaticassembly of the surgical instrument of FIG. 1;

FIG. 3 is an exploded perspective view of the endoscopic portion of thesurgical instrument of FIG. 1;

FIG. 3A is a side plan view in partial cut away of the pusher washersand flange member of the pneumatic system in accordance with oneembodiment of the present invention;

FIG. 4 is an exploded perspective view of one embodiment of the anviland cartridge assembly of the surgical instrument of FIG. 1;

FIG. 5 is a side plan view in cross section taken along line 5--5 ofFIG. 1 showing the frame and pneumatic assembly in the unclamped andunfired position;

FIG. 6 is a transverse view in cross section taken along line 6--6 ofFIG. 5 oriented toward the proximal end of the instrument showing theframe and pneumatic assembly in the unclamped position;

FIG. 7 is a side plan view in cross section showing the frame andpneumatic assembly in the clamped and unfired position;

FIG. 8 is a transverse view in cross section taken along line 8--8 ofFIG. 7 oriented toward the proximal end of the instrument showing theframe and pneumatic assembly in the clamped and unfired position;

FIG. 9 is a top plan view in cross section taken along line 9--9 of FIG.5 showing the frame and pneumatic assembly of the surgical, instrument;

FIG. 10 is a transverse view in cross section taken along line 10--10 ofFIG. 5 oriented toward the distal end of the instrument showing aportion of the frame and pneumatic assembly;

FIG. 11 is a side plan view in cross section showing the frame andpneumatic assembly of the present invention in the clamped and fixedposition;

FIG. 12 is a side cut away view in cross section showing the operationof the pneumatic assembly of the present invention as it is fired;

FIG. 13 is a side cut away view in cross section taken along line 13--13of FIG. 12 showing the valve and gas tube of the pneumatic assembly;

FIG. 14 is a side plan view in cross section showing the frame andpneumatic assembly of a surgical instrument incorporating an adjustablestroke mechanism;

FIG. 15 is a side cut away view in cross section of a surgicalinstrument incorporating a metering assembly between the valve andpiston assembly;

FIG. 16 is a side plan view of a channel member in accordance with oneembodiment of the present invention;

FIG. 17 is a transverse view in cross section taken along line 17--17 ofFIG. 16 oriented toward the proximal end of the channel member;

FIG. 18 is a transverse view in cross section taken along line 18--18 ofFIG. 16 oriented toward the distal end of the channel member;

FIG. 19 is a bottom plan view of an anvil member in accordance with oneembodiment of the present invention;

FIG. 20 is a top plan view of the anvil member of FIG. 19;

FIG. 21 is a side view of the anvil member of FIG. 19;

FIG. 22 is a top plan view of a cam bar adapter in accordance with oneembodiment of the present invention;

FIG. 23 is a side plan view of the cam bar adapter of FIG. 22;

FIG. 24 is a from plan view of the cam bar adapter taken along line24--24 of FIG. 22 oriented toward the proximal end of the adapter;

FIG. 25 is a side plan view in cross section of the cartridge housing ofFIG. 4;

FIG. 26 is a top plan view of the cartridge housing shown in FIG. 25;

FIG. 27 is a side cut away view in cross section of the cartridgehousing of FIG. 25 taken along line 27--27 of FIG. 26;

FIG. 28 is an exploded perspective view of another embodiment of thecartridge assembly of the surgical instrument in accordance with thepresent invention;

FIG. 29 is a perspective view of the assembled cartridge assembly ofFIG. 28;

FIG. 30 is a perspective view in partial cross section of an anvil andcartridge assembly in accordance with the present invention;

FIG. 31 is a perspective view in partial cross section of an anvil inaccordance with the embodiment of FIG. 30;

FIGS. 32 through 34 are side plan views in partial cross section of asequence of operations for the anvil and cartridge assembly of FIG. 30;

FIG. 35 is a perspective view of another self contained gas poweredsurgical instrument in accordance with the present invention;

FIG. 36 is an exploded perspective view of the handle portion of theself contained gas powered surgical instrument of FIG. 35;

FIG. 37 is an exploded perspective view of the endoscopic portion andjaw structure of the self contained gas powered surgical instrument ofFIG. 35;

FIGS. 38 and 39 are side cross-sectional views of the firing triggerwith integral lockout in the unfired and fired positions; and

FIGS. 40 and 41 are side views of the cartridge and support structureshowing the operation of the clamp lockout structure.

FIG. 42 is a perspective view of one embodiment of the clamp lockoutmechanism.

FIGS. 43-44 are side elevation views partially shown in section of theembodiment of FIG. 42 in operation;

FIG. 45 is a side elevation view, partly shown in section of a firstpreferred clamp lockout mechanism;

FIG. 46 is a cross sectional view taken along lines A--A of FIG. 45;

FIGS. 47-49 are side elevation views partially shown in section showingthe operating sequence of the embodiment of FIG. 45;

FIG. 50 is a perspective view of a second preferred embodiment of theclamp lockout mechanism partially shown in section; and

FIGS. 51-53 are side elevation views partially shown in section showingthe operation of the embodiment of FIG. 50.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although the principles of the invention are applicable to other typesof self contained gas powered surgical fastening instruments, theinvention will be fully understood from the following illustration ofits application to endoscopic surgical fastening instruments of the typeshown, for example, in Green et al. U.S. Pat. No. 5,040,715. Also,although the invention is applicable to surgical fastening apparatushaving other constructions, the invention will be illustrativelydescribed in its application to surgical staplers in which a staplecartridge containing a plurality of staples, staple drivers and staplefiring means in cooperation with anvil means respectively form opposingjaw structure located on a distal end of the stapler for capturing andjoining tissue.

I. Overall Construction and Operation of the Firing Assembly

As shown in FIG. 1, a self contained gas powered endoscopic surgicalinstrument 50 constructed in accordance with the principles of thisinvention includes a frame 52 and an endoscopic portion 54. An anvil 56and cartridge assembly 58 are mounted in a distal end 60 of endoscopicportion 54 and are preferably interchangeable with other anvil/cartridgeassemblies (as discussed in greater detail hereinbelow) to perform awide variety of surgical fastening procedures as needed.

Anvil 56 and cartridge assembly 60 are manually controlled by means ofan articulating handle 62 in the frame 52. This handle 62 interconnectswith anvil 56 by means of a linkage disposed in endoscopic portion 54such that when handle 62 is moved from its open position (FIG. 1) to aclosed position (FIG. 7), anvil 56 is moved into close approximationwith cartridge assembly 58. This operation will be discussed in greaterdetail below.

Turning now to FIG. 2, an exploded perspective view of the frame andpneumatic system is shown in accordance with the present invention.Frame 52 includes a first housing member 64 and a second housing member66 enclosing a pneumatic system shown generally at 68. Articulatinghandle 62 is pivotally connected at a distal end thereof to clamp tube70 at pivot point 72. Longitudinal grooves 74 formed in both first andsecond housing members 64, 66 adjacent pivot point 72 slidably receivemolded shuttles 76 attached to handle 62 at 72. The molded shuttles 76are pivotally connected to either side of the pivot point 72 on thedistal end of handle 62 and serve to guide the distal end of handle 62in a longitudinally distal direction as the handle is compressed.

A pair of articulating links 78 interconnect an intermediate portion ofhandle 62 to a pair of projections 80 formed on an upper surface ofhousing members 64, 66 respectively. A handle return spring 82 extendsbetween handle 62 and housing members 64, 66 by means of spring anchorpins 84, one of which is disposed in handle 62 and the other extendingbetween projections 80 which also serve to pivotally connectarticulating links 78 to projections 80. This spring 82 assists inreturning handle 62 from its closed position to its open position.

The proximal end of handle 62 is preferably diagonally formed away fromhousing members 64, 66 so as to enable the surgeon to more easilyrelease the handle 62 from its closed position. This is done by placingthe hand under the proximal end of the handle and lifting. A texturizedor serrated portion 86 may advantageously be formed on an under surfaceof the proximal end of handle 62 to enhance gripping of the handle 62.

Pneumatic system 68 is wholly contained within housing members 64, 66and includes a container 88 of relatively low pressure gaslongitudinally slidably mounted therein. The pressure of the gas incontainer 88 during operation of the stapler is typically less thanabout 200 p.s.i.g. and preferably in the range from about 80 p.s.i.g. toabout 160 p.s.i.g. Any suitable non-toxic gas can be used including butnot limited to halogenated hydrocarbons which are gaseous at roomtemperature, e.g., fluorinated hydrocarbons such as Freon 12 orchlorinated hydrocarbons such as Freon 152A. Container 88 dispenses therelatively low pressure gas through stem 90, valve 92 and gas tube 94when the firing trigger 96 is depressed. Spring 97 is positioned betweencontainer 88 and valve 92 and serves to hold the container 88 away fromvalve 92. Valve 92 is fixed within housing members 64, 66 and islongitudinally adjustable by means of set screw 93. (FIG. 13) Thisfeature permits the position of valve 92 to be longitudinally changed tocompensate for manufacturers' variations in length among containers 88between a distal end and the proximal end of stem 90.

Disposed above container 88 within housing members 64, 66 is a pneumaticactuator 98. Actuator 98 includes a pneumatic cylinder 100 which is heldin place by opposing pins 99 and which is closed at its proximal endexcept for ferrule 102 and is open at its distal end, as well as apneumatic piston 104 mounted for reciprocal motion in cylinder 100parallel to the longitudinal axis of endoscopic portion 54. Cylinder 100is preferably circular in transverse cross-section however other shapeswould function acceptably well.

Piston 104 is pneumatically sealed to cylinder 100 by "O" ring 106molded of polyethylene or the like. Gas dispensed from container 88 issupplied to pneumatic actuator 98 via gas tube 94 which admits the gasto cylinder 100 through ferrule 102 behind piston 104 to drive piston104 distally in the cylinder. The distal end of piston 104 is adapted toengage the firing mechanism of the surgical apparatus as will bedescribed in greater detail below.

Referring to FIGS. 2, 5 and 7, firing trigger 96 is pivotally mounted ina proximal end of housing member 64, 66 by pivot pin 108. Spring 110 ispositioned adjacent pin 108 and serves to bias the firing trigger 96proximally into the prefiring position. A trigger rod 112 extendsdistally from firing trigger 96 longitudinally to engage piston slide114 positioned in a lower portion of piston 104. Piston slide 114comprises a substantially "U"-shaped channel which fits into acorresponding groove 116 formed in piston 104. Piston slide 114 isspring loaded in a proximal direction by spring 118 and includes atransverse projection 120 on a lower distal end thereof which engagesthe distal end of trigger rod 112.

Referring now to FIGS. 2 and 5-11 and initially to FIGS. 2, 5-8 and 11,a rocking lever 120 is pivotally mounted on transverse slide pin 122 andis adapted for transverse movement relative to slide pin 122 between anengaged position prior to firing (FIGS. 7-9) and a disengaged positionwhen articulating handle 62 is open (FIGS. 5 and 6). Cam slide 124 isvertically mounted in first housing member 64 for reciprocal movementbetween an upper and lower position (FIGS. 6 and 8 respectively) andserves to move rocking lever 120 between the engaged position (FIG. 8)and the disengaged position (FIG. 6). Thus, until the articulatinghandle 62 is closed causing cam slide 124 to move rocking lever 120 intothe engaged position, the instrument 50 cannot be fired.

Cam slide 124 is normally biased in its upper disengaged position by camslide spring 126 mounted in vertical groove 128 of first housing member64 (FIGS. 5 and 6). In this upper position, cam slide 124 extends upwardbeyond first housing member 64 (FIG. 6) to engage articulating handle 62as it is moved to a closed position (FIGS. 7 and 8). Cam slide 124further includes a camming surface 130 which contacts a correspondingcamming surface of camming block 132 mounted on slide pin 122. Cammingblock 132 is loaded against cam slide 124 by slide spring 134 and movesrocking lever 120 transversely on slide pin 122 between an engagedposition and a disengaged position. Referring to FIG. 8, as thearticulating handle 62 is compressed toward housing members 64, 66 inthe direction of arrow 135 it contacts cam slide 124 moving it downwardand causes camming surface 130 to move camming block 132 and rockinglever 120 transversely into an engaged position in line with piston 104.

Turning to FIGS. 5, 7-9 and 11, once the articulating handle 62 has beenfully compressed (FIGS. 7-9) rocking lever 120 is disposed in alignmentwith piston slide 114 and can be pivotally moved about transverse slidepin 122 to engage pusher disk 136 at the distal end of container 88.When the instrument is in the clamped configuration, depression of thefiring trigger 96 moves trigger rod 112 distally in the longitudinaldirection causing piston slide 144 to engage and pivot rocking lever 120which, in turn, engages pusher disk 136 and moves container 88longitudinally into contact with valve 92 to dispense gas and propelpiston 104 in the distal direction. See FIGS. 11, 12 and 13.

As piston 104 moves distally, rocking lever 120 remains in its pivotedfiring position by contact with the bottom surface of piston 104. A gap138 is formed in the bottom surface of piston 104 near the proximal endthereof which gap effectively allows rocking lever 120 to disengage frompiston 104 and pivot back to a position wherein container 88 is releasedfrom engagement with valve 92, stopping the flow of gas into pneumaticcylinder 100.

Return springs 140, 142 disposed in endoscopic portion 54 drive piston104 back to its initial prefired position. A camming surface 144 isformed in a distal end of gap 138 and causes rocking lever 120 to movetransversely out of engagement with piston 104 as it returns proximallyand the rocking lever 120 moves to its original prefired position (FIG.7).

FIG. 14 shows an alternate embodiment of the present inventionincorporating an adjustment mechanism 146 which permits the instrument148 to be selectively adjusted to change the length of the firing andreturn strokes of piston 150. This advantageous feature permits the userto selectively fire a predetermined length of staples using a singleinstrument. For example, if the user installs a staple cartridgeassembly having six rows of staples, each row having a longitudinallength of 60 mm, the instrument is set using adjustment mechanism 146 tofire the staples in the entire length of the cartridge. Cartridgeshaving some lesser length of staples may be inserted and fired dependingon the needs of the user.

The adjustment mechanism 146 shown in FIG. 14 includes a belt 152 whichtravels around a pair of longitudinally disposed pulleys 154, 156. Afirst linkage rod 158 engages the top portion of belt 152 and extends toa gap adjustment member 160 slidably positioned in piston 150. A secondlinkage rod 162 engages the bottom portion of belt 152 and extends to aslidable piston stop 164 disposed within pneumatic cylinder 100.

Belt 152 may be rotated in either the clockwise or counterclockwisedirection by rotating knob 166 disposed in housing 172 between pulleys154 and 156. This permits the user to preselect the firing stroke of theinstrument 148. For example when belt 152 is rotated counterclockwise,the firing stroke piston stop is being driven proximally by secondlinkage rod 162 and the gap 168 wherein the rocking lever 120 disengagesthe pneumatic actuator 98 is correspondingly widened. This permits theuser to fire shorter rows of staples without changing cartridgeassemblies. Conversely, when belt 152 is rotated in a clockwisedirection, the firing stroke is progressively lengthened this allowingthe user to fire up to the entire length of the rows of staples in thecartridge assembly.

In the instrument 148 shown in FIG. 14, the firing stroke may be presetto fire either 30 mm or 60 mm rows of staples from a 60 mm lengthcartridge assembly. These preset positions correspond to camming pins186 and 170 respectively which serve to disengage first rod linkage 158from belt 152 so that belt 152 is not rotated during the firing strokeof the pneumatic actuator 98.

Turning now to FIG. 15, another beneficial feature is shown incorporatedinto the pneumatic system in accordance with the present invention. Thisfeature comprises a pressure sensor 174 disposed in line between thevalve 92 and the pneumatic cylinder 100 to sense and/or regulate the gasdelivered from container 88 to the cylinder 100. During surgicalprocedures involving the driving of surgical fasteners and particularlywhere a knife is used to divide fastened tissue, it is important thatwhen the trigger is depressed there is sufficient gas remaining in thecontainer 88 to complete an entire piston firing stroke. If insufficientgas were available, the piston may not be able to fasten and/or dividethe desired length of tissue, necessitating duplication of theprocedure. Pressure sensor 174 serves to premeasure the amount of gasnecessary to achieve the desired piston stroke before activating topermit the gas to flow into the pneumatic cylinder 100 to drive piston104.

It is also envisaged that a counter mechanism can be incorporated tooperate in conjunction with the pneumatic system 68 in order to monitorthe number of firings which the instrument has been subjected to. Thisnumber can be visually displayed to the operator so that, for example,after a given number of firings, the instrument can be overhauled orreplaced. Similarly, where a relatively small number of firings areavailable from a single gas container, this counter mechanism willassist the operator in recognizing when the container is nearingexhaustion. In a particularly desirable embodiment, the countermechanism can be combined with a lockout mechanism which will disablethe firing mechanism after a preselected number of firings.

As seen in FIG. 15, upon depressing firing trigger 96, gas is releasedfrom container 88 substantially as described hereinabove. However, afterleaving stem 90 and passing through nozzle 92, the gas contacts pressureplate 176. Pressure plate 176 is preset by means of spring 178 to keeporifice 180 closed until a predetermined gas pressure is realized at thepressure plate 176. Once this threshold pressure is realized, pressureplate 176 moves out of contact with orifice 180 permitting gas to passtherethrough and into pneumatic cylinder 100 to drive piston 104distally. In the event that insufficient gas is available to reach thisthreshold pressure, pressure plate 176 continues to block orifice 180and the instrument cannot be fired.

Referring now to FIG. 3, there is shown in exploded detail an endoscopicportion 54 in accordance with one embodiment of the present invention.At a proximal end, piston 104 is longitudinally reciprocally slidablethrough clamp tube 70 and extends into the proximal end of cover tube182. The distal end of piston 104 is provided with an attachment flange184 which flange 184 mounts a plurality of pusher washers 186 thereon.These pusher washers 186 are formed in a substantially abbreviatedfrustoconical cross-section from a resilient material such as, forexample, commercial spring steel or type 302 stainless steel. Thesewashers are typically known as Belleville Spring Washers availablethrough SPEC Associated Spring Raymond, Barnes Group Inc. The washersare especially suited for high loads in small spaces and may be combinedin varying sequences to achieve numerous load carrying possibilities. Inthe embodiment of FIG. 3, a total of twelve pusher washers are usedsubstantially as shown in FIG. 3A with duplicate washers arranged in sixopposing sets. A spring support washer 188 is positioned on flange 184distal to pusher washers 186 and serves to engage the proximal ends ofinner and outer return springs 140 and 142. Lock washer 189 holds thewashers in place on flange 184. Attachment flange 184 has a chamfereddistal tip and is configured and dimensioned to be received between theproximal fingers 190 and channel 192.

As shown in FIGS. 3 and 16-18, channel 192 is an elongated structureslidably mounted in endoscopic portion 54 for reciprocal longitudinalmotion therein. As mentioned above, channel 192 has fingers 190 at aproximal end thereof to receive attachment flange 184 of piston 104. Ata distal end of channel 192 there is provided a fork 194 defining a slot196 therebetween. Fork 194 has a pair of opposed ramping surfaces, 198and 200 respectively, the purposes of which will be described in greaterdetail below. Proximal to fork 194 is abutting structure 202 whichstructure extends below the lowermost dimension of fork 194.

Referring back to FIG. 3; an extension sleeve 204 is disposed within thecover tube 182 and is fixed on a proximal end thereof to clamp tube 70.Sealing member 206 is mounted on flange 208 of clamp tube 70 and servesto sealably isolate the frame 52 of the instrument 50 from theendoscopic portion 54. Inner and outer return springs, 142 and 140respectively, are contained within upper extension spacer 210 and lowerextension spacer 212 which are, in turn, fixed within the extensionsleeve 204. Spring support washer 188 abuts the proximal ends of innerand outer return springs 142 and 140 and, when the instrument is fired,transmits the energy of the compressed springs 142, 140 to the piston104, returning it to its prefired position.

Support structure 214 is also disposed within extension spacers 210, 212and function to releasably receive anvil and/or cartridge assemblies ininstrument 50. Support structure 214 is retained in place withinextension spacers 210, 212 by transverse support key 216. An anvilreturn spring 218 is affixed to an underside portion of supportstructure 214 and assists in the retention of the anvil within theinstrument.

A collar assembly, shown generally at 220, is attached to the respectivedistal ends of external sleeve 204 and extension spacers 210, 212. Thisassembly 220 includes a forward collar tube 222, a collar tube spacer224 and a rear collar tube 226, each having camming bosses 268, 270formed on inner surfaces therein as will be described in greater detailbelow.

In the embodiment of the present invention shown in FIGS. 1-3, theendoscopic portion 54 is rotatable relative to the frame 52 by means ofrotation knob 228 (FIGS. 1 and 2). This rotation knob 228 is in the formof an abbreviated frustoconical structure having a bore therethroughdimensioned to receive a proximal end of cover tube 182. At a proximalend of knob 228, knurling 229 may be provided to facilitate rotation.Once connected to cover tube 182, rotation of knob 228 causes the distalworking end of the instrument to rotate.

Referring now to FIGS. 4 and 19-27, there is illustrated an anvil 230and cartridge assembly, shown generally at 232, in accordance with oneembodiment of the present invention. Anvil 230 is an elongated piecewhich is mounted in support 214 by means of proximal legs 250. At itsdistal end, anvil 230 has an anvil plate 236 with a tissue contactingsurface 238 having staple forming depressions 240 (See FIG. 19). At itsproximal end, anvil 230 is provided with an upper camming surface 242and locking surface 244, which surfaces are engagable with correspondingtop arcuate camming surface 246 formed in forward collar tube 222.Transverse opposing projections 248 are formed on legs 250 at theproximal end of anvil 230 and provide an engagement point for anvil 230to be cammed between an open and closed position by the interaction ofcamming surface 242, locking surface 244 and top arcuate camming surface246 of collar tube 222. Preferably, the radius of curvature of the toparcuate camming surface 246 is shorter than the radius of curvature ofcamming surface 242 and equal to the radius of curvature of lockingsurface 244. This configuration prevents flexing of the camming surface246 of collar tube 222 and lateral movement of the anvil as it is beingcammed closed.

Anvil plate 230 also has a longitudinal center groove 252 to permitpassage of a knife 254. Anvil 230 is further provided with parallelaligning surfaces 256 positioned below camming surface 242. Thesealigning surfaces are dimensioned to fit outside projections 258 oncartridge housing 260 upon closure of the anvil 230. The engagement ofthe aligning surfaces 256 and the corresponding projections 258 ofcartridge housing 260 serves to more accurately and securely align anvil230 and cartridge housing 260 upon closure. Further visual confirmationof alignment is facilitated by a pair of parallel longitudinalindentations 262 formed in the distal end of anvil 230. Theseindentations 262 allow the surgeon to view the closed structure of theanvil 230 and cartridge assembly 232 to confirm accurate longitudinalalignment thereof.

Further, as shown in FIG. 21, the horizontal plane formed by tissuecontacting surface 238 intersects the horizontal plane formed by thecamming portion of the proximal end of anvil 230 at an obtuse angle "α".This angular orientation pre-cambers the anvil 230 and balances theclosure force applied by the anvil 230 to the captured tissue.

First and second camming surfaces, 264 and 266 respectively, are formedin a sidewall portion of the proximal end of anvil 230. These cammingsurfaces engage camming bosses, 268 and 270 respectively, formed oninner opposing sidewalls of collar tube assembly 220. Anvil 230 isinserted into collar tube assembly 220 and projections 248 engage withsupport structure 214 bring camming surfaces 264 and 266 into engagablealignment with camming bosses 268 and 270. Cartridge assembly 232,discussed in greater detail hereinbelow, is fixedly inserted into collartube assembly 220 and remains stationary relative to anvil 230.

During fabrication of anvil 230, the anvil blank may advantageously beformed by metal injection molding and thereafter coined and coated asdescribed below. A wide variety of staples and fasteners arecontemplated for use with the present apparatus. In a preferredembodiment for use with titanium fasteners, it has been found thatforming of the fasteners in the staple forming depressions 240 isfacilitated by applying a hard, relatively smooth surface on the stapleforming portion of the anvil 230. The preferred method of application ofthis surface is by electroless plating, with the surface being formed ofa metallic alloy such as, for example, nickel, gold, silver, titaniumnitride or chromium. Where nickel is used, the applied surface ispreferably in the range of 100μ-2000μ in thickness with an optimumthickness of between 200μ-500μ. Ranges for other alloy may varydepending upon their inherent characteristics.

Where nickel is to be applied, the preferred method is an electrolessplating method including the steps of: electrocleaning the anvil in acyanide-containing cleaner, reversing polarity at predeterminedintervals, preferably about every 10-15 seconds, at a current of about50 amps/ft² ; rinsing thoroughly; rinsing in a solution containing astrong acid, preferably 20% HCL, dipping several times; immersing theanvil in a NiCL strike tank for plating, preferably for two to fourminutes at a current of about 50 amps/ft² ; rinsing; and immersing theanvil in an electroless Ni bath, preferably Enthone 418 or 431, for atime sufficient to achieve the desired plating thickness. For example,at a deposition rate of 0.0005 in/hr, a time of between 30 to 40 minuteswould be required to achieve a thickness of about 300μ±50μ. Othercoating procedures are also contemplated including vapor deposition,etc. and are encompassed by the present invention.

Turning now to FIGS. 4 and 22-27, there is illustrated a replaceablecartridge assembly 232 in accordance with the present invention. Thecartridge assembly 232 includes: a cartridge housing 260; a cartridge272 having a plurality of pushers 274 and staples 276 disposed inlongitudinal arrangement therein; and a plurality of cam bars 278removably disposed in cam bar adapter 280 and a cam bar alignment tab282 as well as a knife 254 mounted in the cam bar adapter 280.

Referring specifically to FIGS. 25-27, the proximal end of cartridgehousing 260 comprises a substantially elongate channel of semi-circularcross-section having a forward and rearward portion 284 and 286respectively. A transverse locking slot 288 is formed in rearwardportion 286 and serves to engage and retain support structure 214. Uponinsertion into collar tube assembly, the forward end of supportstructure 214 is biased by the rearward portion 286 of cartridge housing260 until the support structure 2 14 engages locking slot 288.

Rearward projection 290 is formed in the base of cartridge housing 260.The function of this projection 290 will be described in greater detailbelow. Forward of the projection 290 is a bore 292 which receives shearpin 294 formed on cam bar adapter 280 (FIGS. 22-24). A pair of crimps296 is provided in opposing sidewalls of the rearward portion of theproximal end of the cartridge housing. These crimps 296 provide afriction fit with cam bar adapter 280.

The forward portion 284 of the proximal end of cartridge housing 260 hasprojections 258 which, upon closure of the cartridge assembly 232 andanvil 230, contact and align with anvil aligning surfaces 256 asdescribed above.

The distal end of the cartridge housing 260 comprises a channelstructure of substantially rectangular cross-section. This distal endconstitutes the cartridge receiving portion and is dimensioned toreceive cartridge 272 therein. Bores 298 and projection 300 serve toengage pins and bores respective in the cartridge 272 so as to align andretain the cartridge 272 within the cartridge receiving portion of thecartridge housing 260.

Referring to FIG. 26, the cartridge receiving portion in the distal endof cartridge housing 260 and the proximal end of cartridge housing 260are joined at an obtuse angle θ defined by the intersection of thehorizontal planes of both the proximal and distal ends of the cartridgehousing 260. This angular orientation serves to pre-camber the cartridgeassembly and facilitates accurate closure and alignment of the jawelements as well as more secure retention of subject tissue.

The cartridge 272 includes longitudinal groove structure 302 forreceiving and guiding knife 254 and a plurality of pushers 274 abuttingstaples 276. The staples 276 are advantageously arranged in sixlongitudinal rows with three rows positioned on either side of groovestructure 302.

Two pairs of longitudinal slots are formed in the cartridge housing 260and are adapted to receive a pair of double cam bars 278 therein. Eachpair of cam bars serving to drive three corresponding longitudinal rowsof staples. Further, the two pairs of longitudinal slots extend to theend of cartridge 232.

Cam bars 278 are provided with a cam surface 304 in an upper distal endthereof and an overhanging ledge 306 with vertical surface 308 in alower distal end. This overhanging ledge 306 is dimensioned to extendinto the longitudinal slots to a point wherein the vertical surface 308of the overhanging ledge 306 drops down and abuts the forward edge 310of the cartridge retaining portion of the cartridge housing 260 when thecam bars 278 move to their distal fired position. At their proximal end,cam bars 278 are provided with hook structure 312 for releasablyengaging cam bar adapter 280.

Referring now to FIGS. 22-24, there is shown multiple views of the cambar adapter 280 in accordance with one embodiment of the presentinvention. The cam bar adapter 280 comprises a forward section 314 and arearward section 316. The forward section 314 is substantiallyrectangular in shape and has a central longitudinal groove 318 formedtherein and dimensioned to receive the longitudinal groove structure 302therein when the cam bar adapter is urged to its forwardmost position.Flanges 320 and shelves 322 serve to removably retain the proximal endof cam bars 278.

The rearward section 316 is rectangular in shape with projections 324formed in the proximal end thereof. The rearward section is dimensionedto be receivable within the slot formed in fork 194 in channel 192. Theprojections 324 are dimensioned to engage ramping surface 198 to allowthe fork 194 to ride up and over the projections 324 when the fork 194is moved in the distal direction.

Vertical bore 326 and longitudinal groove 328 are formed in the rearwardsection 316 and serve to retain and hold the shank of knife 254. Shearpin 294 is integrally formed with cam bar adapter 280 on a bottomsurface thereof and, in the prefiring position, is aligned with andreceivable into bore 292. Also, in this prefiring position, the rearwardsection 316 of the cam bar adapter 280 is disposed over rearwardprojection 290 to effectively shield engagement of abutting structure202 with projection 290.

Turning now to FIGS. 28-34, there is shown a second preferred embodimentof an anvil and cartridge assembly in accordance with the presentinvention. Referring to FIGS. 28 and 29, the cartridge assembly 330comprises a cartridge housing 332 mounting a cartridge 334 containing aplurality of pushers 336 disposed beneath staples 338, in a distal endthereof. A pair of cam bars 340 are positioned in the cartridge housing332 and are adapted to move longitudinally through parallel longitudinalslots formed in cartridge 334. A camming surface 342 is formed on anupper distal end of cam bars 340 with an overhanging ledge 344 formed ona lower distal end. Vertical ledge 346 is formed proximal to overhangingledge 344 and is adapted to engage the distal end of cartridge housing332 when the cam bars 340 are driven to their full distal position. Acam bar alignment tab 348 engages both cam bars 340 and holds them inparallel alignment. A cam bar adapter 350 is adapted to fixedly receivethe shank portion of cam bars 340.

Cartridge 334 is designed with three longitudinal rows of staples witheach row of staples being offset from adjacent rows as shown in FIG. 28.This embodiment of the present invention does not utilize a knifestructure and is designed to place rows of staples in body tissue.

Referring to FIGS. 30-31, an anvil 352 is shown having substantially thesame design as anvil 230 described hereinabove with respect to theprevious embodiment. The primary difference is that the distal portion354 of anvil 352 is narrowed to receive and form three longitudinal rowsof staples in contrast to the six rows of staples and knife accommodatedby anvil 230. Anvil 352 includes a pair of longitudinally extendingparallel legs 356 having transverse opposing projections 358. Parallelaligning surfaces 360 are formed in sidewalls of anvil 352 and serve tooverfit and align anvil 352 on cartridge housing 332. First and secondcamming surfaces 362, 364 are formed in sidewalls of anvil 352 proximalto parallel aligning surfaces 360 and serve to engage camming bosses268, 270 formed in forward collar tube 222 and rear collar tube 224,respectively.

Upper camming surface 366 is formed on an upper surface of anvil 352proximal to distal end 354 with locking surface 368 formed distallyadjacent upper camming surface 366. Both the upper camming surface 366and the locking surface 368 are adapted to engage and be cammed by toparcuate camming surface 246 formed in the distal end of forward collartube 222.

FIGS. 35-39 show a further embodiment of the present invention similarto that shown in FIGS. 1-15 with the jaw structure of FIGS. 28-34.Referring to FIGS. 35-36, the handle portion of this embodiment furtherincludes annular seals 101, 103 provided between the distal end of frame52 and the proximal end of cover tube 182. These seals serve to furtherinhibit the escape of insufflation gas from the operative site. Seals107 and 109 are positioned adjacent the proximal and distal ends,respectively, of clamp tube 70 to better seal off insufflation gas fromthe area of the piston 104.

A counter mechanism is also disposed in handle portion 52 and comprisesa counter ratchet 400 attached to trigger rod 112 and a leaf spring 402mounted in housing 66 so as to engage the teeth on the bottom surface ofcounter ratchet 400. Numerical indicators are longitudinally disposed onan outer surface of the counter ratchet 400 and correspond to the numberof times the instrument has been fired. An access plate 404 having aviewing window 406 therein is positioned in the outside surface ofhousing 66.

In operation, each time the instrument is fired the leaf spring 402engages a respective proximally located tooth of the counter ratchet400, effectively sliding the counter ratchet 400 distally to align thenext lower number in viewing window 406. The counter mechanism of thisembodiment further includes a locking feature whereby the trigger button96 is retained in the fired position when the leaf spring 402 engagesthe most proximal surface of the counter ratchet 400 and prevents thefiring rod 112 from returning to its proximal unfired position.

This embodiment of the present invention further includes an integraltrigger button rotary safety mechanism comprising a rotary safety shaft408 disposed within a roller 410. The rotary safety mechanism isrotatably positioned in trigger button 96 with the roller 410 extendingout beyond the plane of the back surface of trigger button 96.Projections 412 are eccentrically formed on both sides of rotary safetyshaft 408 and extend out beyond the plane of the side surfaces of thetrigger button 96. Spring 414 serves to normally bias the rotary safetymechanism with the projections 412 disposed in their distalmostorientation.

Referring now to FIGS. 38 and 39, in the instrument's unfired position(FIG. 38) projections 412 are in their distalmost position and aredisposed in direct alignment with the proximal ends of the housingmembers 64, 66. In this position, the trigger button 96 cannot beaccidentally depressed to fire the instrument. In order to disengage thesafety mechanism, the roller 410 is moved in the direction of arrow 416which serves to rotate projections 412 from their distalmost position(FIG. 38) to their proximalmost position (FIG. 39) effectively allowingtrigger button 96 to be depressed to fire the instrument. As soon asroller 410 is released, spring 414 returns the safety mechanism to itsnormal position to prevent subsequent accidental firings.

FIG. 37 shows the endoscopic portion and the jaw portion of the surgicalapparatus of FIG. 35. The anvil 418 of this embodiment is provided witha pair of angled proximal legs 420. This feature permits the anvil 418to be opened wider to more easily receive tissue between the anvil 418and cartridge 58. The angled proximal legs 420 preferably extend at anangle of between 0° and 30° from the longitudinal plane of the anvil.

One embodiment of a clamp lockout structure is shown in detail in FIGS.37, 40 and 41 incorporated into the support structure 214 and upperextension spacer 210. The clamp lockout structure comprises a leafspring 430 having a diagonally downwardly extending projection 432attached thereto. A slot 434 is formed through the top surface ofsupport structure 214 and is adapted to engage and receive projection432 whenever the support structure is not longitudinally aligned. Thisclamp lockout structure is designed and configured to prevent theinstrument jaws from closing on tissue unless the cartridge and/or jawelements are properly emplaced within the apparatus.

In operation in the stapling apparatus of FIG. 37, leaf spring 430 andprojection 432 are normally disposed above support structure 214. Theproximal ends of the cartridge 334 and the anvil 418 are insertedthrough collar tube 222 and brought into engagement with the distal endof support structure 214. (See FIG. 40) In the event that the cartridge334 and/or the anvil 418 are not properly and/or completely insertedinto engagement with support structure 214, the resulting angulardisposition of the support structure 214 brings slot 434 into alignmentwith projection 432. (See FIG. 41) As the operator attempts to depressthe handle 62, the extension spacer 210 begins to move distally causingprojection 432 to enter slot 434 and become entrapped thereineffectively preventing any further distal movement of the extensionspacer 210 and, in turn, preventing approximation of the anvil 418 andthe cartridge 334.

The following embodiments of the clamp lockout structure are describedwith reference to the endoscopic stapler embodiment of FIGS. 1-4.

Turning now to FIGS. 1-4 and 42-44, a latch mechanism 450 is shown whichoperates by directly engaging collar tube 220. Latch mechanism 450includes a basically U-shaped mounting section 452 having a pair ofoutwardly projecting mounting tabs 454, an elongated rounded nosesection 456 and a downwardly projecting lock member 458. Spring 460 isprovided to bias latch mechanism 450 radially outward toward collar tube220. Collar tube 220 is similar to the collar tubes describedhereinabove as are the other related parts, such as, for example, thecartridge assembly etc. When used with the latch mechanism embodimentsof FIGS. 42-49, collar tube 220 is provided with a notched opening 221.Notch 221 is positioned directly below downwardly extending lock member458 when anvil 230 (FIG. 4) is in an unapproximated or open position andcollar tube 220 is in its proximalmost position.

In operation, as cartridge assembly 232 is slid into collar tube 220,rounded nose portion 456 of latch mechanism 450 rides up an angled rearsurface portion 233 of cartridge 232 to completely cam lock member 458out of engagement with notch 221 in collar tube 220. Lock member 458moves between a first position wherein no cartridge assembly is presentor a present cartridge assembly is improperly inserted (not fullyinserted) such that the lock member is engaged with, and locking, collartube 220 (FIG. 43) and a second position wherein a cartridge is presentand fully seated such that the lock member is cammed out of engagementwith collar tube 220 (FIG. 44). In this embodiment of the latchmechanism, rear surface portion 233 of cartridge assembly 232 does notcontact downwardly projecting lock member 458.

A first preferred embodiment of a clamp lockout structure is shown indetail in FIGS. 45-49. As can best be seen in FIG. 45, latch mechanism462 generally includes a U-shaped mounting section 464 having a pair ofmounting holes 466, an elongated blunted nose section 468 extendingoutwardly and forwardly from U-shaped mounting section 464 and adownwardly projecting lock member 470 extending radially outward fromnose section 468. The lock member 470 has an angled forward portion 472and a hooked rear portion 474.

Referring to FIGS. 45 and 46, latch mechanism 462 is mounted on supportstructure 214 by means of holes 466. A spring 476 is suspended fromsupport structure 214 and engages a pair of side projections 478 onlatch mechanism 462. Spring 476 normally biases latch mechanism 462radially outward towards collar tube 220.

In operation, the stapling apparatus incorporating the clamp lockoutmechanism of FIG. 45, is initially devoid of cartridge assembly 232.Downwardly projecting lock member 470 is biased by spring 476 into notch221 of collar tube 220 thus locking collar tube 220 against any relativelongitudinal movement. Inserting cartridge assembly 232 into collar tube220 will cause lock member 470 to be cammed out of engagement with notch221 thereby freeing collar tube 220 for movement. Specifically, as shownin FIGS. 45 and 47-49, when cartridge assembly 232 is initially slidinto collar tube 220, rear surface portion 233 of cartridge 232 abutsand engages nose portion 468 of latch mechanism 462. Sliding cartridgeassembly 232 proximally causes blunted nose portion 468 to ride up onrear surface portion 233 drawing lock member 470 radially inward andpartially out of collar notch 221. After an initial insertion movement,continued insertion of cartridge assembly 232 (FIGS. 47-48) causes rearsurface portion 233 to engage angled forward portion 472 of lock member470 drawing lock member 470 further inward out of collar notch 221.

When cartridge assembly 232 is fully seated within the instrument, ascan be seen in FIG. 49, latch mechanism 462 is fully cammed out ofengagement with collar tube 220. At this point anvil 230 and fullyseated cartridge assembly 232 can be approximated by sliding now freecollar tube 220 distally. Once anvil 230 and cartridge assembly 232 havebeen approximated the instrument can be fired. It will be noted thatlatch mechanism 462 remains cammed out of engagement with collar notch221 in collar tube 220 so long as cartridge assembly 232 remains fullyseated within the instrument. Thus anvil 230 and cartridge assembly 232may be reapproximated even after the instrument has been fired.

Turning now to FIGS. 50-53 a second preferred embodiment of the clamplockout structure is shown in detail. As can be seen in FIG. 50, clamplockout structure 480 includes a hooked shaped pawl 482 pivotablymounted on lower extension spacer 210 by means of pin 484. Spring 486 isprovided to bias pawl 482 radially inwardly away from collar tube 220.When anvil 230 and cartridge assembly 232 are in the open position,collar notch 221 in collar tube 220 is located directly beneath adownwardly extending hooked front section 488 of pawl 482.

In the absence of a fully inserted and unfired cartridge assembly 232,as can best be seen in FIG. 51, a channel member 192 initially restsupon pawl 482 and outwardly urges pawl 482 in the direction of arrow Ginto notch 221 to engage or lock up collar tube 220. Thus where anunfired cartridge assembly 232 is not present in the instrument, collartube 220 is prevented from sliding and thus approximation of anvil andcartridge assembly 232 is prevented.

The operation of the second preferred embodiment of the clamp lockoutstructure is best illustrated in FIGS. 51-53. As shown in FIG. 52, whencartridge assembly 232 is inserted into collar tube 220, opposed rampingsurfaces 198, 200 of channel member 192 ride up and over cam bar adaptor280 which is initially rearwardly positioned at a proximalmost positionwithin cartridge assembly 220. Channel member 192 is lifted by cam baradaptor 280 allowing spring 486 to inwardly move pawl 482 out ofengagement with notch 221 of collar tube 220. At this point, collar tube220 is now free to slide back and forth to approximate the anvil 230 andcartridge assembly 232. As indicated hereinbelow, when the instrument isfired, channel member 192 moves distally pushing cam bar adaptor 280distally ultimately driving staples 276 from cartridge assembly 232 intothe anvil 230. Releasing handle 62 causes channel member 192 to moveproximally pulling cam bar adaptor 280 proximally. As can be seen inFIG. 53, as cam bar adaptor 280 moves proximally within cartridgeassembly 232, cam bar adaptor 280 abuts inwardly crimped edges 296 ofcartridge assembly 232 which prevents further proximal movement of cambar adaptor 280. As the handle 62 is fully released, channel member 192continues to slide proximally disengaging from cam bar adaptor 280 anddropping down onto pawl 482. After stapling the tissue, anvil 230 andcartridge assembly 232 are opened by sliding collar tube 220 proximally.As the collar tube 220 is slid fully to the rear, notch 221 in collartube 220 is positioned directly below now outwardly urged pawl 482 whichthus reengages notch 221 in collar tube 220. In this manner collar tube220 is once again "locked out" from operation.

In contrast to the embodiments of FIGS. 43-49, the second preferredembodiment of the clamp lockout structure reengages or relatches collartube 220 after the instrument has been fired. Specifically, so long ascam bar adaptor 280 is not in a proximal position sufficient to engageand lift the channel member 192, channel member 192 will urge pawl 482radially outwardly into engagement with notch 221 of collar tube 220when collar tube 220 is in its rearward or proximal most position.

While the clamp lockout structure embodiments of the present inventionare illustrated with respect to the gas powered surgical fasteninginstrument of FIGS. 1-4, it can be readily appreciated that the latchmechanisms may be applied to any powered or manually operated surgicaldevices incorporating sliding collar members or other means whichapproximate an anvil and a detachable cartridge unit, or other similarclamping, grasping or stapling jaw structures.

Additionally, it is contemplated within the scope of the presentinvention to provide other means for latching mechanisms to directlyengage the collar tube, such as, for example, with radially inwardlydirected projections, tabs, etc. on the collar tube.

II. Operation of the Instrument

In use, the endoscopic portion of the instrument is inserted into thebody, preferably through an endoscopic tube. It is further preferredthat the endoscopic tube apparatus be capable of maintaining a sealedpneumoperitoneum, with the internal sealing member of the housingfurther maintaining this seal despite introduction of the instrument inaccordance with the invention into the endoscopic tube. As a practicalmatter, the jaws of the instrument are closed for insertion into theendoscopic tube, either by pinching the anvil and cartridge prior toinsertion or by closing the articulating handle to cam the jaws closedprior to insertion.

After insertion into the endoscopic tube, the endoscopic portion may berotated in order to appropriately orient the instrument at the staplingsite. Rotation of the endoscopic portion relative to the body may beattained by rotating the instrument, as a whole, by rotating theendoscopic portion relative to the frame using rotation knob 228 (SeeFIG. 1), or by a combination thereof.

Referring to FIGS. 3, 5-8 and 32-34, with the instrument properlyoriented so that the tissue to be fastened is disposed between the openjaws of the instrument, i.e., between the tissue contacting surfaces ofanvil member 230 and cartridge 302, the jaws are closed to clamp thetissue. In the first embodiment, the surgeon presses down on actuatinghandle 62, thereby sliding collar tube assembly 220 distally, via clamptube 70, extension sleeve 204, and extension spacers 210, 212.

Referring to FIGS. 32-34, as collar tube assembly 220 moves distally inthe direction of arrow A from a first position where the top arcuatecamming surface 246 at the distal end of forward collar tube 222 isproximal to camming surface 242, (FIGS. 32-33), to a second positionwhere the top arcuate camming surface 246 is engaged with lockingsurface 244, (FIG. 34), the top arcuate camming surface 246 contacts thecamming surface of the anvil, thereby forcing the anvil to cam viacamming surfaces 264, 266 on camming bosses 268, 270 until the anvil isbrought into close cooperative alignment with the cartridge assembly.FIG. 34 illustrates the instrument with the jaws in a closed position.

After closing the instrument jaws, the instrument is ready to be fired.When the surgeon is ready to emplace the staples and cut tissue, firingtrigger 96 is depressed to actuate the pneumatic actuator 98 asdiscussed in detail above. Piston 104, attached to the proximal end ofchannel 192 is driven distally causing camming surface of forks 194 toride up and over projection 324 of the cam bar adapter 280 and drive thecam bar adapter in a distal direction. Shear pin 294 is severed and thecam bars and knife are driven longitudinally through the cartridge tosequentially drive and form staples and cut tissue.

As piston 104 contacts return springs 140, 142, pusher washers 186 arecompressed on themselves and serve to store energy as the piston movesdistally toward the cartridge assembly. This initial compression occursin the range of between about 20 p.s.i. to about 150 p.s.i. andpreferably within a range of about 30 p.s.i. to about 60 p.s.i. Near theend of the distal stroke of the piston 104, this stored energy isreleased to drive the cam bars 278 through the final distal limits oftheir travel within the longitudinal slots in the cartridge. At thedistal extreme of the longitudinal stroke, the overhanging ledges 306 ofcam bars 278 drop over the edge of the cartridge housing thus abuttingvertical surface 308 with edge 310.

After firing, return springs 140, 142 engage piston 104 and return it toits original position. The return motion of piston 104 causes rockinglever 120 to be cammed aside by camming surface 144 of piston 104. Inthe embodiment containing knife 254 discussed above, the cam bars 278are pulled out of cam bar adapter 280 and remain in position in thelongitudinal slots of the cartridge 334. The cam bar adapter, with knife254 attached, moves proximally within cartridge housing 272 until theouter edges of cam bar adapter 280 impinge on crimps 296.

The cam bar adapter 280 is held in place by crimps 296 while cammingsurface 200 of fork 194 causes the fork to ride up and disengage withprojection 324 of the cam bar adapter. Channel 192 continues to move inthe proximal direction until abutting structure 202 is positionedproximally to rearward projection 290 formed in the floor of cartridgehousing 260. At this point, the entire cartridge assembly 232 isdeactivated.

In the event that the surgeon should accidentally attempt to again firethe instrument without replacing the deactivated cartridge with a newunfired cartridge, the resulting distal longitudinal motion of thechannel 192 moves abutting structure 202 into contact with rearwardprojection 290 effectively preventing further movement of forks 194toward cam bar adapter 280.

After firing, articulating handle 62 is raised with the assistance ofhandle return spring 82 which action retracts collar tube assembly 220.This retraction causes anvil 230 to cam out of engagement with cartridgeassembly 232. Similarly, raising of articulating handle 62 causes camslide 124 to move upward disengaging the pneumatic firing mechanism.

In order to replace the cartridge assembly, the instrument is withdrawnfrom the patient. The cartridge assembly is released and may be removedby pulling it distally out of collar tube assembly 222.

To reinsert a new cartridge assembly, the proximal end of the cartridgeassembly is inserted into collar tube assembly 222 until engaging andlocking into support structure 214. The instrument is now ready forreinsertion and continued use.

Operation of the instrument with the cartridge and anvil assembly shownin FIGS. 28-31 is substantially similar to that described above. Tubulartissue to be ligated and/or divided is captured within the anvil 352 andthe cartridge assembly 330 such that the tissue is transversely orientedtherebetween. The cartridge assembly 330 and anvil 352 are approximatedby means of camming surfaces 362, 364 and camming bosses 268, 270, asdescribed above. The staples 338 are fired, ligating the tissue.

Unlike the previous embodiment, the cartridge assembly 330 does notinclude a knife and therefore does not require that the cam bars beretracted by channel 192. In operation, the distal end of channel 192engages the proximal end of cam bar adapter 350 and drives cam bars 340to their extreme distal position (FIG. 34). In that position,overhanging ledges 344 drop over the distal end of cartridge housing 332and remain there. As the piston 104 retracts, channel 192 moves awayfrom cam bar adapter 350 and retracts to a position proximal to rearwardproject 290, this leaving cam bars 340 and cam bar retainer 350 in thedistal position within cartridge assembly 332. Opening, removal andreplacement of the deactivated cartridge are effected in substantiallythe same way as described above with respect to the second alternativeembodiment.

It will be understood that various modifications can be made to thevarious embodiments of the present invention herein disclosed withoutdeparting from the spirit and scope thereof. For example, various sizesof the instrument are contemplated, as well as various types ofconstruction materials. Also, various modifications may be made in theconfiguration of the parts. For example, in the first embodiment theelongated slot for allowing access to the thumbwheel may be placedalternatively in the left body portion or right body portion. Thereforethe above description should not be construed as imitating the inventionbut merely as exemplifications of preferred embodiments thereof. Thoseskilled in the art will envision other modifications within the scopeand spirit of the present invention as defined by the claims appendedhereto.

What is claimed is:
 1. A surgical apparatus for approximating surgicaljaw structure comprising:a) a handle; b) an elongated portion defining alongitudinal axis and extending distally from said handle; c) first jawmeans mounted to said elongated portion and having a first tissueengaging surface for supporting tissue; d) second jaw means, mounted tosaid elongated portion, having a second tissue engaging surface and adistal end and a proximal end, said second jaw means being mounted withrespect to said elongated housing such that at least the distal end ofsaid second jaw means is movable in directions generally transverse tosaid longitudinal axis between an open position spaced from said firsttissue engaging surface and a closed position wherein said second tissueengaging surface is in close cooperative alignment with said firsttissue engaging surface; e) a camming member associated with saidelongated portion and engagable with said second jaw means for movingsaid second jaw means between said open position and said closedposition; and f) lockout means associated with said elongated portionfor arresting movement of said camming member, said lockout meansincluding a latch member movably mounted with respect to said elongatedhousing, said latch member being movable from a locked position engagingsaid camming member to an unlocked position wherein said latch member isdisengaged from said camming member.
 2. The surgical apparatus of claim1 wherein said camming member is axially movable with respect to saidsecond jaw means, said camming member having a distal camming surfaceand being movable between a first position in which said camming surfaceis located proximally to the proximal end of said second jaw means, anda second position in which said camming surface is located distally tothe proximal end of said second jaw means, said camming membercooperating with said second jaw means such that when said cammingmember is moved from said first position to said second position, saidsecond jaw means is urged to said closed position.
 3. The surgicalapparatus of claim 2, wherein said camming member is a tubular collardisposed around at least a portion of said elongated portion.
 4. Thesurgical apparatus of claim 3, wherein said latch member in said lockedposition engages a notched opening in said collar in said firstposition.
 5. The surgical apparatus of claim 2 wherein said first jawmeans comprises:a cartridge holding a plurality of ejectable surgicalfasteners; and a cam bar adapter removably mounting means for ejectingsaid surgical fasteners from said cartridge.
 6. The surgical apparatusof claim 5 wherein said lockout means arrests movement of said cammingmember when said cam bar adaptor is located distally of said cam baradaptor's proximalmost position within said cartridge.
 7. The surgicalapparatus of claim 5 wherein said actuating means comprises a pneumaticsystem disposed in said frame and including a self contained supply ofpressurized gas and a pneumatic actuator mechanism associated with saidgas supply, said pneumatic system adapted to actuate said means forejecting said surgical fasteners.
 8. The surgical apparatus of claim 2further comprising means for moving said camming member between saidfirst position and said second position which means for moving saidcamming member includes a manually operated handle and linkage assemblyconnected to said camming member.
 9. The surgical apparatus of claim 1wherein at least one of said first jaw means and said second jaw meansis detachable from said elongated portion.
 10. The surgical apparatus ofclaim 9 wherein said latch member is urged into said unlocked positionwhen said detachable first or second jaw means is fully inserted intosaid elongated portion.
 11. The surgical apparatus of claim 1 whereinsaid lockout means further comprises a spring mounted with respect tosaid elongated portion, wherein said spring acts to bias said latchmember toward said locked position.
 12. The surgical apparatus of claim1 wherein said second jaw means comprises an anvil member removablymounted to said elongated portion.
 13. A surgical apparatus for drivingsurgical fasteners into body tissue comprising:a) a handle; b) anendoscopic portion defining a longitudinal axis and extending distallyfrom said handle, said endoscopic portion including:i) an elongatedhousing having a distal portion which includes a member to support aplurality of surgical fasteners for slidable movement generallytransverse to said longitudinal axis, said distal portion having atissue engaging surface for supporting tissue to be fastened, ii) ananvil member having a fastener forming surface and a distal end and aproximal end, said anvil member being mounted with respect to saidelongated housing such that at least the distal end of said anvil memberis movable in directions generally transverse to said longitudinal axisbetween an open position spaced from said tissue engaging surface and aclosed position wherein said fastener forming surface is in closecooperative alignment with said tissue engaging surface, iii) a cammingmember engagable with said anvil member for moving said anvil memberbetween said open position and said closed position, iv) means forejecting said surgical fasteners from said fastener support member,whereby said fasteners engage tissue positionable between said tissueengaging surface and said fastener forming surface, and v) lockout meansengagable with said camming member for arresting movement of saidcamming member.
 14. The surgical apparatus of claim 13 wherein saidcamming member includes a tubular collar disposed around at least aportion of said housing and said anvil, said tubular collar having adistal camming surface and being movable between a first position inwhich said camming surface is located proximally to the proximal end ofsaid anvil member, and a second position in which said camming surfaceis located distally to the proximal end portion of said anvil member,said tubular collar cooperating with said anvil member such that whenthe collar is moved from said first position to said second position,said anvil member is urged to said closed position.
 15. The surgicalapparatus of claim 14 wherein said lockout means comprises a latchmember mounted with respect to said elongated housing and at least oneof said fastener support member and said anvil member is adapted todetachably engage said housing, said latch member being movable from alocked position engaging said collar in said first position to anunlocked position disengaged from said collar.
 16. The surgicalapparatus of claim 15 wherein said latch member is urged into saidunlocked position when said detachable fastener support member or anvilmember is fully inserted into said elongated housing.
 17. The surgicalapparatus of claim 15 wherein said latch member is in said unlockedposition when said fastener support member is properly mounted withinsaid elongated housing.
 18. The surgical apparatus of claim 14 whereinsaid fastener support member comprises:a cartridge holding a pluralityof ejectable surgical fasteners; and a cam bar adapter removablymounting means for ejecting said surgical fasteners from said cartridge.19. The surgical apparatus of claim 13 wherein said fastener supportmember is removably mounted to said elongated housing.
 20. A lockoutmechanism for use with a surgical instrument having a frame portion, anelongated portion extending distally from the frame portion, a first andsecond jaw mounted with respect to the elongated portion, at least oneof which is adapted for detachable engagement with the elongatedportion, and means for approximating the jaws, said lockout mechanismcomprising: a latch member pivotally mounted on a distal end of theelongated portion, said latch member having a lock member dimensionedand configured to automatically engage and arrest movement of theapproximating means when the at least one detachable jaw is not properlyengaged with the elongated portion.
 21. The lockout mechanism of claim20, wherein the approximating means comprises a camming member slidablymounted with respect to the elongated portion and having structureengagable with said lock member, said camming member slidable between afirst position wherein said first and second jaws are substantiallyspaced apart to a second position wherein said camming member cams oneof said jaws towards said other jaw, said lock member engaging saidcamming member structure in said first position.
 22. The lockoutmechanism of claim 21 wherein said lock member engages a notched openingin said camming member structure in said first position to arrestmovement of said camming member.
 23. The lockout mechanism of claim 22further comprising a spring member mounted on the frame portion andengaging said latch member, said spring member biasing said latch membertowards said camming member.
 24. An improved surgical fasteninginstrument of the type having a frame portion, an elongated portionextending distally from the frame portion, a first and a second jawmounted with respect to the elongated portion, at least one of which isadapted for carrying ejectable fasteners, means movably mounted withinthe at least one jaw for ejecting the fasteners, means for approximatingthe jaws and firing means for activating the eject means, wherein theimprovement comprises: a latch member movably mounted on a distal end ofthe elongated portion and automatically engagable with the approximatingmeans after the instrument has been fired or when the fastener carryingjaw is not operably engaged with the elongated portion and a springassociated with the elongated portion and engagable with said latchmember to bias said latch member toward the approximating means.
 25. Asurgical apparatus for approximating surgical jaw structurecomprising:a) a handle; b) an elongated portion defining a longitudinalaxis and extending distally from said handle; c) a first jaw mounted tosaid elongated portion and having a fastener support member; d) a secondjaw mounted to said elongated portion and having an anvil surface, saidsecond jaw being movable between an open position spaced from saidfastener support member and a closed position wherein said anvil surfaceis in close cooperative alignment with said fastener support member; e)a camming member operatively associated with said elongated portion andengagable with said second jaw for moving said second jaw between saidopen position and said closed position; and f) a latch member movablymounted with respect to said elongated portion and engagable with saidcamming member, said latch member being movable from a locked positionengaging said camming member to an unlocked position wherein said latchmember is disengaged from said camming member.
 26. The surgicalapparatus as in claim 25 wherein said fastener support member isremovably attached to one of said first and second jaws.